Ok, I'll think about some examples.
-Florian
Alexander Potochkin schrieb:
Hello Florian
I must confess that I don't think it is desirable
to generify every class in Swing, so #1 looks good for me
:-)
Two generic parameters add to much of typing, in my opinion
Could you please provide a complete example of a JList
with a custom ListCellRenderer that proves that renderer should be
generified
By the way the more examples the better,
another one which promotes JList generifying
would also help to promote this idea for Swing team members
Thanks
alexp
So, 2 votes for option 3), which is a reasonable one, I think.
Pavel? Anyone else?
-Florian
Am Sonntag, 22. Februar 2009 schrieb Erik Lundqvist:
Hi,
ListCellRenderer should absolutely be generic which rules out option
1 :)
I cannot remember ever using the prototypeCellValue so a bit worried
about
saying too much about how people are using it, but it does not seem
unreasonable that it should be of the same type so I would go for
Option 3
as well which seems the simpler and most common use case.
//erik
2009/2/21 Florian Brunner <fbrunnerl...@gmx.ch>
Hi,
I think adding generics to the ListCellRenderer could also be
useful. The
problem is that in JList
the same cell renderer is used for the items as for the
prototypeCellValue - and the
prototypeCellValue doesn't necessarily have be of the same type as the
items!
So I think we have 3 options:
1) Don't provide a generic cell renderer/ allow only Object as
parameter
for the cell renderer in
JList.
2) Add a second generic parameter. Eg. something like:
class JList <E, P super E>{ ... }
and use P for the prototypeCellValue property as well as for the cell
renderer.
3) Require prototypeCellValue to be of type E. In the probably rare
cases, where this is a problem
one can still specify a common base class of the items and the
prototypeCellValue as the generic
parameter or use a raw type JList.
I think it would be a pity not to provide a generic cell renderer
(1) and
think 2) is inconvenient
and confusing, since in my experiences prototypeCellValue is only used
rarely.
So I'm voting for 3). For which option do you vote? For which reason?
Note I also propose to use:
ListCellRenderer<? super E> cellRenderer
rather than
ListCellRenderer<E> cellRenderer
in JList. This would make it more flexible. Do you agree? (It's
actually
the first time, I think, I
use 'super' with generics myself, but I think this is a good use
case of
it. So any comments are
welcome. ;-) )
-Florian
